The goal of the multidisciplinary Structure of Visual Space Group is to focus on the structural nature of visual space and how it is "constructed," its relation with "external" physical space, correlated brain events, and to corollary theories in modern physics and cosmology.
Anyone wishing to post material on the blog is invited to contact either William Rosar (wrosar@ucsd.edu) or John Smythies (jsmythies@ucsd.edu) of the Center for Brain and Cognition, University of California, San Diego.

Friday, November 19, 2010

Mind and Body, Medieval and Modern: part 2

Saint Thomas Aquinas stood with Augustine on many key points concerning the nature of reality. This includes important points where he stood with Augustine and against Descartes on issues having to do with the specific problems of mind and body. Thus, Aquinas agreed with Augustine that matter sits at the bottom of the hierarchy of the universe. He agreed that a rational creature is superior to a dead body because God gives more to the one than to the other. Aquinas agreed that to be spiritual is to have levels of power and perfection that go beyond what can be captured within matter. He agreed that the human soul comprehends but does not exemplify extension; or rather, the soul exemplifies extension by developing and maintaining the body but not within itself. Aquinas agreed that this is so because the human soul (like God, or an angel) is superior to what does exemplify or display extension within itself. Again, he stood with Augustine against Descartes in affirming the basic division between sense and intellect, with all that this division entails for both the human subject and the nature of reality. For all these reasons, Aquinas stood with Augustine in understanding the situation of mind and body better than Descartes. However, Augustine agreed with Descartes in speaking of the soul as numerically separate from the body and all its parts, although very differently from the way Descartes understood this thesis. Unhappily, given this separation, there is no way to avoid the enormous, and notorious, challenges that have been brought against Cartesian dualism. This point applies to Augustine's version as well. These challenges are so severe that the strongest reason for saying materialism is true of the human person may be phrased as a modus tollens argument. "If materialism is not true, then Cartesian dualism is not false. But Cartesian dualism is clearly false and obviously absurd. Therefore, materialism is true." This conclusion does follow, and the criticism of Cartesian dualism is certainly correct. Consequently, materialism is often accepted as the only theoretical framework worth taking seriously. But there is another possibility. One can deny materialism apart from affirming Cartesian or even Augustinian dualism. Long before Descartes, there was what might be called the theory of the "top down" structure of the human subject. The origins of this theory go back to ancient times. This theory is what Aquinas followed. This "top down" theory is something like a dualism of attributes within a single substance. But this substance is really more mental than material or corporeal. For it is not correct to say that mental attributes belong to the body. The truth is almost exactly the opposite. This theory is much more like Strawson's idea of the person, with mind and body together, as the primary unit. However, the sort of personalism proposed here has the mind as the dominant factor within the person. To speak in a picturesque metaphor, one could almost say the mind reaches down to include the body, and this complex of mind and body is the human person. Perhaps the chief fault of this metaphor is that the mind does not so much reach down as though it were exercising strength. Instead, it would be better to say that the (human) mind spills down or lapses into matter because of its natural weakness. (The human soul is "weak" as needing to be involved with matter instead of being able to stand alone as a pure spirit.) Thus, this theory is almost like idealism, since the body may be said to be a function of the mind, except that the body is fully real. More properly, this theory is to idealism (more or less) what traditional epiphenomenalism is to materialism. For this reason, one might speak of this theory as "reverse epiphenomenalism," and this theory has been spoken of in this way on this basis. Thus, Descartes was right to speak of himself as a thinking thing. But whether thinking allows or excludes extension as an attribute is a separate question. The thing that thinks might turn out to be material, or spiritual, or some sort of hybrid. What is proposed here is that the thing that thinks (the “rational substance”) is a kind of hybrid. Intellect and will belong to the inner spirituality of the person, and this inner spirituality is a level or layer within someone that is above the material. On the other hand, the spiritual soul of the human person is also the "organizing and architectonic principle" of the living animal body. The thing (or “substance”) that is the person is then the rational animal as a living being.This theory may be explicated more fully by going into its historical development. Plato argued against materialism, but he also affirmed full dualism. However, Plato also said that the soul weaves the body around itself. This statement is too clearly metaphorical to be more than merely suggestive as it stands. Then again, one must presumably say that the body is derived from the functioning of the soul instead of having the mental life of the person be developed out of the functioning of the body. If it means anything at all to say the soul weaves the body around itself, it has to mean at least this much. This kind of reverse epiphenomenalism is the third alternative, apart from both materialism and dualism. Plato combined this thesis, that the soul develops and maintains the body, with full dualism. But these theories can be distinguished. After Plato, Aristotle spoke of the soul as the form of the body. What he meant by this idea may be subject to interpretation. On the other side, Aristotle argued against materialism as regards the thinking mind. If he had said the thinking mind is part of the human individual, then he might be committed to saying the soul develops the body. As it is, what Aristotle believed about the thinking mind may also be subject to interpretation. In any event, Aristotle gave the chief dignity to form over matter. A thing's form is the principal basis for the thing to be what it is and to do what it does. So, Aristotle's answer seems to be that the soul develops the body instead of being derived from the body as an epiphenomenon. This theory was clearly the answer given by Thomas Aquinas. Like Plato and Aristotle, Thomas Aquinas argued against materialism on the ground that reasoning transcends matter. But he also opposed full dualism. Instead, Saint Thomas said that the soul is the chief active principle within the person. There are intellectual capabilities because there is more to the (human) soul than what is involved in being the organizing and architectonic principle of the body. Abstract thinking belongs to this superior level within the person. This theory seems to be the best available answer regarding mind and body. One of the strongest reasons in favor of this theory is that it has the most serious advantages of Cartesian dualism, but escapes the four chief objections. This point will be demonstrated by examining each of these four objections in turn. To begin with, there are two obvious problems concerning individual identity. First of all, there is the problem of individual identity as regards diversity from others. For one must ask in what ways things are differentiated to be numerically separate from each other. As Aquinas pointed out, God is diffferentiated from other things by the very fact that He is infinite and they are finite. Things other than God can be differentiated from each other in some material way, or by differing in kind or species, or perhaps in both ways. (Two dogs differ from each other in virtue of material facts, or material stuff, or both. A dog differs from a cat in kind or species, and that fact would be enough by itself to establish them as separate beings.) That is all. Along this line, Thomas Aquinas spoke of angels as (created) pure spirits. But in order to do this, he had to say that each angel differs in kind or species from every other angel. Only in this way can one angel be numerically diverse from another. An angel is created and so is not God. Since angels have no material stuff in them, and no material restrictions upon them, there is only the difference in kind or species to make them separate from each other. Now, if the human mind were truly a separate substance from the body, it would presumably be a pure spirit in the manner of an angel. So, if there were to be a multitude of separate human minds, then they would all have to differ in kind or species from each other. But in fact, the available evidence points very strongly in the opposite direction. Therefore, the evidence is clearly against dualism. On the other hand, this argument fails to reach the kind of "top down" personalism proposed here in anything like the same way. A human person is a sort of material substance, even though it is also much more than this. Thus, a human person is fully subject to multiplicity within the same species, like any other animal but unlike an angel. Second, there is a problem of individual identity as regards continuity through time. What happens when someone falls into a deep coma, so that there is no mental life at all going on inside the person? A dualist must either insist that mental life does not fully cease even in deep coma or admit that the person's life has lapsed in such cases. Either of these answers is at least seriously questionable given the available evidence. For Aquinas, the answer is clear enough. Mental dispositions can exist apart from being exercised, just like any other dispositions. (For example, a man can be intelligent even when he is not thinking, just as a lump of salt or sugar can be soluable when it is not presently being dissolved.) Even if the person “could not be” restored to having mental life, this would show only that the impediments to natural functioning could not be removed by the available healing arts. The person would still exist as a rational substance. Moreover, it would be false to say that the person is then a substance with no qualities or events actually present. So long as there is bodily life, the qualities that arise out of bodily functioning belong to the person, since the nature of the distinctively human person includes the body. These bodily qualities and events are enough for the life of the person to continue as something actually occurrent.To be sure, this second problem weighs much less heavily on Augustine than it does on Descartes. The reason is that Augustine was much more concerned than Descartes to affirm that the soul develops and maintains the body. Therefore, Augustine could stand with Aquinas and say that, in such cases, the soul is still exercising vital functioning over the body, even though no mental life is presently being exercised.Third, there is the problem about how the mind of a human person works. Once again, if the human mind were truly a separate substance from the body, it would presumably be a pure spirit in the manner of an angel. In that case, the mental life of a human person would presumably be free from any weaknesses or limitations derived from matter. But this is clearly false. Moreover, such weaknesses and limitations, so far from being externally imposed on the mind, appear to derive from the inner nature of the mind. Furthermore, these restrictions seem to reach even those distinctive operations of intellect and will with the strongest claim to transcend matter. Thus, once again, full dualism appears contrary to the available evidence. On the other hand, the theory proposed here is fully compatible with all this evidence. A human person looks very much like an animal with some distinctively spiritual capabilities laid on top of its nature as an animal. The reason is that this is what a human person is in fact. Intellect and will exist only in conjunction with the person's nature as an animal, even though they transcend this nature. For this reason, abstract thinking and deliberate choice occur only within the context defined by someone's life as an animal (where this life is taken to include imagination and emotion as well as sensory perception). All this remains so even though these activities are ultimately irreducible to any kind of purely animal functioning. What this involves can be illustrated from the specific concerns over visual experience. Aquinas agreed with Augustine that the soul to which intellect and will belong is the same soul that animates the body. They agreed also that the soul is nonspatial, albeit as transcending spatial restrictions and not as lacking anything. But then it seems mysterious how the soul can accommodate the vast spaces that show up in visual experience. Augustine answered that this is so because of the soul's superior power. Aquinas would (almost) agree, but in a different way. Saint Thomas considered that, properly speaking, it is the human person to which mental life belongs, rather than the soul as such. Along this line, the soul's superior power allows the spaces that show up in visual experience to be accommodated by establishing and holding the body as an integral part of the person. Insofar as something literally spatial is needed to accomodate these spaces, this something is present, and it is the body of the person. Sensory experience (visual or otherwise) is a function of the body, just as abstract thinking and deliberate choice are functions of the spiritual soul. But since body and soul together make up the human person as a single unit, these functions are combined to make up the mental life of the person as something unified. What if it were to be proposed that the soul itself is literally spatial? The answer to this proposal involves going back and considering a prior question. Why should one affirm any soul in the first place, instead of just attributing mental life to the body? One answer is that self aware consciousness seems to require something deeply unified as the subject to which it belongs, and the body is not sufficiently unified. Descartes seems to have been right about this. But then the soul cannot itself be spread out in the same way as the body, or there would be the same problem all over again. This "top down" theory provides for Descartes's insight but avoids the problem about experiencing space. Fourth, and most notorious, there is the problem about interaction. Even if there could be a separate human mind with the required attributes, one would still have to ask how it is related to the body. Since mind and body are supposed to be fully constituted substances, they would have to interact causally. No mechanism for such interaction is even minimally plausible. However, the basic problem is far deeper than this. The problem is that the theory turns out to be demonstrably incoherent as regards the body. For the body has to be a fully constituted substance, and yet it must be naturally ordered to receive causal influence from the mind. This influence appears not to be externally imposed on the body: it appears instead to fit right into the functioning of the body. Thus, the functioning of the body must be profoundly incomplete in some way to make room for this influence. But this result is contrary to the claim that the body is a fully constituted substance. On the other hand, this evidence may even support the theory proposed here, for the body is not claimed to be a fully constituted substance within itself. Instead, the soul is the organizing principle of the body. The mental life of the human person can govern bodily activity by influencing how bodily processes are organized. There remains some question about the mechanism, but the basic problem of conceptual logic is eliminated. Yet the body seems to be fully organized within itself as a material system. No spiritual activity appears to be required for the body to be what it is and do what it does as a body. The answer to this objection depends on observing a fine distinction. The human body is organized within itself in the sense that the material system works out on its own terms as a material system. However, the body exists as a unified whole only because it is the body of some living person. The soul is the organizing and architectonic principle of the body, but not as though the body needed some magical glue to hold it together. Instead, the body is deeply unified and integrated as a living thing, instead of being a mere machine. The body is a unified whole in virtue of being alive. But the body is animated with the distinctive life of a person. Thus, the basis for the human body to exist and operate as a whole also includes capabilities that go above and beyond what belongs to the functioning of material things as material. It is in this way that the soul acts as the form of the body. Will this answer work out? Paradoxically, it can be made to stand if materialism can avoid being absurd on its face. Any sophisticated materialism has to allow higher animals, and especially human subjects, to be more than machines. For mechanism cannot contain or support the mental life of a dog or a cat, let alone that of a man or a woman. The obvious answer is that all these are living beings instead of mere machines. But then this point about the advantage of being alive cuts both ways. Different types of beings may be alive in different modes and have various capabilities on that basis. In the case of the human subject, the mode in which the animal is alive turns out to be exalted enough to allow for even distinctively spiritual functioning. That is all. "Top down" personalism is vindicated on this basis. Along this line, there is no substitution within the human person of spiritual activity for material functioning of the body. What has to be understood here is that the idea of "top down" structure is taken very seriously as regards the human person and indeed the nature of reality as a whole. Lower levels work out correctly on their own terms as far as may be, and higher levels work by means of lower levels as far as may be. In the present case, intellect and will cannot be wholly reduced to, or constructed from, the lower levels of the human person. (That is what it is for these faculties to transcend those lower levels.) But still, intellect and will work largely by means of emotion, imagination, sensory perception, et cetera. (A man may implement or promote the functioning of his intellect and will by imposing discipline on these subordinate functions, in terms of forming pictures in his mind, directing or calming his feelings, and so on.) Again, the work of imagination, et cetera, is accomplished by means of complex patterns and processes of neural functioning, and this functioning is accomplished by means of low level metabolism, and this metabolism works by means of "nitty gritty" electrochemistry, and so on right down to the underlying quantum physics (or whatever the truth turns out to be). At no point is there any substitution of higher level functioning for that of the lower level. Given all this, one of the strongest arguments for materialism is easily answered. Yes, of course the activities of intellect and will are strongly correlated with neural electrochemistry. Since the higher levels of the person work by means of the lower levels as far as may be, what these higher levels do or fail to do will be largely influenced by what does or does not happen on the lower levels. Similarly, what the craftsman does or fails to do will be largely influenced by what does or does not happen to his tools. But even so, the craftsman is clearly superior to his tools. So here in like manner, intellect and will are superior to neural electrochemistry. Then again, Saint Thomas can give this answer. What Descartes can say is much more problematic.

63 comments:

There is a lot to take in here David. I thought that I would raise two points though. First, with respect to Strawson, I always read him as being a bit of a Kantian, do you disagree with me here, or do Aquinas and Kant have more in common than I supposed? A second point involves the issue of individuation of souls for Descartes. In The Passion of The Soul he claims that the soul is associated with the pineal gland, since that gland, unlike other structures of the brain is not paired. There is a fairly natural reading of this passage as holding that the soul has a spatial location in the mind, in which different souls (even if spatially unextended) could have different spatial locations and hence be differentiated this way. Do you know of any passage from Descartes where he specifically repudiates such a reading?

Has no one in philosophy or science acknowledged the various refutations of materialism that were written and published in the 19th century, more than 1000 years after Augustine? If science chooses to ignore them, apparently it does so with impunity, thinking it of no consequence. Well, the consequences may simply be insoluble conundrums in which it finds itself, taking comfort through a kind of psychological "denial" that the (empirical) answer is "just around the corner," or by explaining it away.

The old phrase "sensus communis" ("common sense") is apt in light of David's deliberations, because the common ground for ordinary experience, knowledge of the world, and the products of thought is known through conscious qualities. Even the most abstract of thoughts has some sort of conscious substance, and that substance is qualitative in nature and, I would argue, is extended as any substance is ex definitione.

David's appeal to the "weakness" of mind and soul is intriguing, because it recalls Eccles' ideas about "mind influences" being so in "The Self and Its Brain." The idea of "amplification" occurs to me in this connection, that if we think of mind as being analogous to a "weak" signal amplified by matter in variegated ways, the process begins to take on a quasi-physical character that might be acceptable to most scientists.

Again, John Wheeler defines "observation" as being an "irreversible process of amplification" of a quantum state. Amplification is a key concept in QM, and might be interpreted to mean that mind exists in something like a quantum state and that, much like quantum "influences," to become manifest ("real," rather than just potential) at the classical level, requires the "machinery" of the strong force (the nuclear force) to "amplify" it--the "chains," as it were.

Again, I come back to the fact that our whole ontogensis (thus morphogensis) could be viewed as an amplification in *spatial magnitude,* from a microscopic fertilized ovum, to the fully grown organism many orders of magnitude larger. Clearly the mind of a fertilized ovum is not capable at that point in development to do much in the way of perceiving, at least as we ordinarily conceive it, let alone thinking.

How then can one exclude biological differentiation from this discussion, mirroring in a way the "Big Bang" originating from a minute point a t = 0?

Yes, Robert, there is a lot to take in here, and I am sorry for the difficulty. As for Strawson, it has been said that, in Individuals (of which chapter 3 is relevant here), he "employs essentially Kantian methods to arrive at Aristotelian conclusions." I was concerned with the Aristotelian conclusions, for Aquinas would say his theory of the soul is a further development of what Aristotle said. However, there is a noteworthy similarity with Kant. It turns out that Kant affirmed the traditional division between sense and intellect, if not so strongly as Aquinas and the other traditional people, then at least much more than many of the early modern thinkers.As for Descartes, it is ironic that you should cite his Passions of the Soul. Just before his baloney about the pineal gland, he lays out clearly that the soul "has no relation to extension, or to the dimensions" of the matter of its body (PS, pt. 1, sec. 30). Again, he says that the soul is joined to the whole body but exercises it functions especially at the pineal gland. This is not the word of one who is looking to spatial location as the basis for numerical differentiation.

"Substance is extended ex definitione." Oh, really? William, what definition of substance are you using when you say this? Traditionally in Western philosophy, one could understand by the word "substance" (1) something that exists within itself (and thus can be more or less of a "standalone unit"), or (2) something that can persist through change, or (3) something that can have any of a range of mutually exclusive attributes. None of these definitions has any obvious implication of being extended. But perhaps you have in mind something very different by the word "substance" in this context?

I am aware of the passages which you cite David, and I agree that in isolation a natural reading is the one that you give. Consideration should also be given though to what Descartes says in the Sixth Meditation about the phantom limb phenomenon (where one still seems to feel pains in one's toes after the leg has been amputated) that we feel things as if they are located throughout the whole body due to connections of the nervous system into the brain, and for Descartes to the pineal gland. Thus, I read Descartes as saying that the soul is joined to the rest of the body by the nervous system, but is actually located in the pineal gland. As for the passage of having "no relation to extension, or to the dimensions" my reading is that he is just referring to lack of spatial extension here, not of spatial location, but maybe we can either agree to or disagree to disagree here.

Well Robert, you may be right. Of course the soul must be spatially located in some way, given that this particular soul is associated with this particular body and no other. The question is, what way? Now, it may be that Descartes thought the soul to be spatially located in the same way as the body. (I suspect he did not distinguish the questions well enough to answer on that point.) But even if he did think this, it looks like that will not help him with the question of individuation. In the Second Meditation, Descartes figured he was nothing but a thing that thinks, which thing might be wholly disembodied. Indeed, he figured he might exist even though there should be no observable world, and thus no space or matter, at all. In view of all this, the natural and obvious conclusion is that Descartes would have to say the mind or soul is already fully constituted as a separate substance prior to being spatially located. But then spatial location cannot be the basis for its individual identity. Then again, the thesis that the soul is spatially located in the same way as the body might help with explaining their interaction. But even so, it would be mysterious how something with zero size and no shape interacts with an extended material body.

My good friend and colleague H.H. Price, erstwhile Wykeham Professor of Logic in the University of Oxford, recorded his opinion about Cartesian Dualism. He held that there is no logical problem in postulating that extended and unextended entities can causally interact. The problem, as he saw it, was that Descartes did not give a proper description of consciousness. That which Descartes felt to be his unextended mind ensconsed “like a pilot in a vessel” was really his Self ensconsed, not in his body, but in his body image. Price recognized that visual images are mental entities, and are both extended and located in space—in a space of their own different from physical space. His theory, however, differs from that put forward by C.D. Broad and myself, and later by Bernard Carr and Jean-Pierre Jourdan. Price suggested that phenomenal events and physical events are causally related, but that there are no spatial relations between their respective spaces. Broad, Carr, Jourdan and I suggest that there are both causal and higher-dimensional spatial relations between the two.The great chemist Joseph Priestly (1777) was the first to suggest the non-Cartesian concept that at least parts of phenomenal consciousness (i.e. visual and somatic sensations and images) are material and occupy space. He complained that the Cartesian concept of mind described precisely nothing and added ”I am therefore obliged to conclude, that the sentient principle in man, containing ideas [in Locke’s sense to include sensations], which certainly have parts, is not the simple, indivisible, and immaterial substance that some [e.g. Descartes] have imagined it; but something that has real extension and therefore must have the other properties

I think, David, that the sense of 'might' which you refer to regarding the Second Meditation, is clearly just epistemic in character; in other words, for all he knows, with certainty, at this point according to Descartes is that he might not have a body. As far as I can see this entails nothing about any metaphysical possibility of a separate existence.

Well, Robert, yes, it is true that the epistemic possibility Descartes latches onto does not really prove much about any metaphysical possibility of separate existence. What Descartes believed on this point is notoriously another question. But there is an important way in which the historical issue is not worth pursuing further in this context, for Cartesian dualism fails in any event. First of all, it is not wholly clear that any concrete being could be actually real and have spatial location but not extension. (A mathematical point is of course merely an ideal construct.) But even if Descartes believed your trick about being located and not extended as the basis for what he said, and even if the trick would work, and even if this trick would solve the problems about individuation and interaction, all that would still not be enough. Only the first and fourth of the problems I listed would be solved even at best. The second and third problems would remain (regarding continuing identity through deep coma and the observed nature of human mental life), and that fact is enough to wipe out Cartesian dualism.

One thing we should bear in mind is that before he set out on his voyage of discovery on the Beagle, Darwin was studying for the clergy at Cambridge. Though Cousin Richard and his followers would like to claim Darwin as one of their own, I don't see that this is a fait accompli by any means: http://en.wikipedia.org/wiki/Charles_Darwin

That being so, in company with the metaphysical history upon which Decartes built, at what point do we see science abandoning all the metaphysical tradition upon which natural philosophy was constructed? Again, what does it do to all that conceptual development to simply remove God from the equation? No one has answered my previous question in this regard.

I want to also comment on David's point about consciousness in deep coma, or in other conditions in which brain function is heavily compromised: It is not at all clear, nor unequivocal, what people in those states experience. So it is not necessarily the case that their experienced selves disappear during such states at all, anymore than they seem to in NDE in which vital signs are flatlined.

There is the metaphysical tradition on which natural philosophy was constructed. What happens to this theoretical structure when God is removed from the equation? Yes, indeed. I should like to research more along this line by going through Stanley Jaki's Gifford Lectures (The Road of Science and the Ways to God). In the meantime, what the wisest men would say, I do not know, but I should have to say Sartre has pretty well laid it out for us. Sartre had his problems, but he had the merit of trying to be consistent. As he pointed out, it will not work to say there is no God at the top, but all else is the same. No, but if God should go, then a whole lot of other things go along with him. Sartre is renowned or notorious for saying the moral law goes, but he realized that much more than that is at stake. Almost all the orderly structure of the universe would vanish into blue thin air. This includes causal structure, so there would be no natural laws and no natural kinds. But really, there is not even any need to bring in Sartre. "There is no god but Chance, and Darwin is its prophet." This is the real religion of Cousin Richard & Company. Well, given chance as the deepest basis for everything, Richard and his crowd can try to explain the best way they can why there seems to be the regular order of lawful structure. Their standard noise about evolution as the answer will not work, for evolution would in fact be derived from the summation of minor random variations within a highly ordered system, and the order of the system is what has to be explained. So, when God is denied, the whole basis for natural philosophy is down the drain right now. There is the answer to your question. Yet I am not sure why we need to get into all this in order to work through what Thomas Aquinas said about mind and body.

Presumably what the two Saints had to say about mind and body rather generally concerns the topic of the blog? I'm just trying to cut to the proverbial chase to understand how this bears either directly or indirectly on that--not that it isn't wholly interesting in terms of the mind-body problem and dualism in general. Is it your intention, David, to in some way work deductively from certain general propositions down/back to the structure and nature of visual space? I guess I don't have a clear sense of what constitutes "relevance" in this context.

All right, fair enough. I can begin to illustrate relevance by saying something about an earlier comment on this Part II. Aquinas agreed with Joseph Priestly that "the sentient principle in man" is not immaterial but is something that has real extension. This sentient principle is the living material body of the human person. For it is the human person as a whole to which mental life belongs. Only the distinctive functions of intellect and will belong to some level or layer within the person above the material. The person's mental life is unified because the person is unified. (When the layer above the material is sundered from the body, that failure of unity is called death.)I think Augustine was largely right, Aquinas was even more right, Priestly was right, and Descartes was largely wrong. Given this, what can I say about perceptual space in general, or visual space in particular? I think perceptual space has something literally spatial as the subject to which it belongs, and this something is the material body. Visual space is developed as a construct out of the functioning of the body, just as the integration of sensory experience in general belongs to the living body. Sensory experience as thus integrated feeds up into the self aware consciousness of the person, which belongs to the level above the material.To be sure, visual space differs in character from the external space of real material bodies, but this fact is of limited importance. Naive realism is false, but sophisticated realism is true, on the basis that (when all goes well) visual impressions correspond rightly to what is there behind the experience. Similarly, temperature as experienced differs in character from the reality of heat and cold. But this tactile experience can be veridical as corresponding rightly to the reality that affects the sensory organs. Again, nothing beyond the living material body is needed to contain or support this tactile experience, even though it differs in character from the reality that stands behind it.As for higher dimensions and subtle bodies, well, maybe so. But as for myself, it is just that there is no need to posit or believe in these exotic things, so far as I can see.

Nicely put, David. It may be possible, in principle, to cleave apart the perceptual world from the mental world, as we see in the agnosias that have been discussed here--not to mention in senility, in which perception of a sort seems to occur, but "nobody's home." It is perhaps rather that information is extracted from the perceptual world, and that process involves a mind. If that mind is gone (or largely gone), the sense may continue to function, but 'fail to reason from what they sense,' to paraphrase Sherlock Holmes. While the *effects* of reasoning are perceptible in some sense, their source seems not. The "unconscious" as Jung defined it surrounds consciousness, and seems to be the source of all that is mind-like or rational, rather than the old empiricist doctrine which suggests that the mind only receives from the senses.

I fear no argument will sway the non-believers, but it would be interesting to see what sort of rejoinder they have to removing God from the equation, once they might fully understand the scope of metaphysical underpinnings upon which scientific concepts rest (if unwittingly), and that removing talk of God (to put it simply) rather pulls the proverbial rug out from under the whole scientific edifice. Remember Whitehead's remark about science's "naive faith" (in itself) that I have quoted now twice.

If the atheists (or agnostics) don't like a monotheistic god, what then of classical thought with its pantheon of deities, upon which similarly rests their metaphysics, and which in turn, rests so much of medieval philosophy as a synthesis with Judeo-Christian thought? What happens when one removes *those* deities from purely classical reasoning and metaphysics?

One further comment: I don't think we ordinarily subjectivize visual space, viz. as "my" visual space, or yours. Visual space is regarded ordinarily as something we seem to resolve by looking--it is something beyond us, in some sense. So I would not assent to your contention, David, that it is connected with a whole person. Or, to use Gordon Allport's nice word, visual space is not part of a person's *proprium.* We've talked some about this in the Center for Brain and Cognition in connection with what I maintain is a disorder of proprium called apotemnophilia, in which otherwise healthy individuals seek parts of their limbs amputated (or paralyzed or de-enervated), finding them to be superfluous, even though the limbs are perfectly healthy, and the people ostensibly normal feeling in them.

Neurologists, in general, distinguish sharply between the "material body" (which we do not experience in somatic sensation) and the "body image" (that which we do experience). As the great Viennese neurologist said "...the empirical method leads immediately to a deep insight, that even our own body is beyond our immediate reach, that even our own body justifies Prospero's words 'We are such stuff as dreams are made on, and our little life is rounded with a sleep'". Wolfgang Kohler made a similar distinction between "my body as an experience" and "my organism as an object in the physical world".In which case I do not see that we can say that visual space derives its spatiality from the "living body". Under normal circumstances visual space derives its spatiality from activity in the occipital lobe in the brain, because, if the occipital lobe is put out of action by injury, visual space is abolished (as in cortical blindness). Likewise the spatiality of the body image ordinarily derives from activity in the parietal lobe—a phantom limb is abolished if the relevant part of the parietal lobe is removed. However, under unusual circumstances, such as in the case of Jean-Pierre's NDE patients, these rules may not hold.

Alas, the neurological terminology is not even very adequate, because properly "image" in the context of the body should be the equivalent of a "visual image" in the realm of *imagination.* Thus I prefer "perceived body" or "perceptual body" instead. I suspect that the word "image" was used due to some form of naive realism on the part of neurologists. But a phantom limb corresponds more to the residual sight that people experience after peripheral blindness of peripheral origin, than it does to anything we would call an "image." The phantom limb is not a "body image" as being something that exists independently of peripheral input, but is due to some residue of normal function, not obliterated because the somatosensory cortex remains intact after amputation or traumatic limb loss.

The problem with then positing *physical* counterparts to these perceptual things is where the trouble begins, as I see it, because as Ray Tallis's chapter on the "Disappearance of Appearance" explains quite vividly, the physical world as conceived by physics has no appearance--it has no sensory qualities of any kind. So just what are these "physical objects" which the philosopher of perception faithfully believe exist? As Eddington pointed out many decades ago, mostly they consist of empty space--hardly something that matches the impression of our perceptual body, for one.

These are all distinctions made long since the Middle Ages--even post Enlightenment I dare say--and I am not sure because of that where they figure in this larger metaphysical discussion.

Oh, well, you see, when I spoke of the "living body" as the basis for visual space, I meant to refer to all the parts of the body as included within the body, and I meant to refer to the vital functioning of all the parts as included within the life of the body as a whole. So, what I said about the living body would cover the occipital lobe, and what I said about the functioning of the body would cover the activity of the occipital lobe. Again, in this context, what I meant by the "living body" is what Wolfgang Kohler meant by the "organism" in the quotation. I was not thinking of the specific experience of one's own body.

Quite so, David, but how do you reconcile these various hypostases which, like all physical "objects" according to modern physics--or even ancient physics--consist only of "atoms and the void," i.e., have no appearance and consist mostly of empty space? I suspect these things actually refer to the body of perception, as perceived, from which all such concepts as "living body," "organism," etc, all likely refer--in other words, natural philosophy is based on a form of naive realism (probably mainly third person NR), taking the perceptual world to be the physical world existing--somehow--beyond perception.

As I repeat these same thoughts over and over here, I am not sure my point is getting across to the assembled body reading!

Just a seat-of-the-pants conjecture, but I suspect science (natural philosophy) really grew like Topsy *away* from religious philosophy, as science became more empirical and less rationalistic in nature. But that is just a wild guess (if not a not wholly untutored one). So the movement away from God may not have been wholly intentional, but was just following a certain way of doing things through observation. As the skeptics and atheists demand that we produce God before their eyes, or evidence of Him, it rather follows if one extrapolates from that demand that the modus operandi that reflects is not consistent with a rationalistic theism which is not subject to empirical exploration or confirmation.

Well, William, we can test whether your points are getting across. To put it crudely, your concern seems to be captured by saying naive realism is one of your pet peeves. Is this correct? If so, then I remind you I have already come out against naive realism. But if not, then I am at a loss.

"Body image" is just the term in use at the moment in neurology, dating I think from Schilder's "The Image and Appearence of the Human Body" (1942). As Bill points out it is not a very good term, as the body image is not an image in the ordinary sense. "Perceptual body" has the disadvantage that some philosophers insist that what is perceived in all cases is a physical object. I think "experienced body" is better, because that is what it is.When discussing what the physical world is "out there", it seems prudent to distinguish between the world itself and how physicists describe it ("mostly empty space"). Realist philosophers, such as G. W. Moore, hold that it is the physical world is that which we perceive (unless we are followers of Bishop Berkeley). In this whole process of perception Edmond has suggested that sensations play a phenomenal role but not an epistemic role. At least we all seem to be agreed that naive realism is out.

My pet peeve is not naive realism, but putative physical realism, and how it defines realism. The average person believes that the physical world is just like the one they perceive, but there are just things about it (like atoms, molecules and radiation) that they can't "see," whereas nothing could be further from the truth. All of us lapse into this naive view much of the time, which should tell us something about ordinary conceptions of reality.

We seem able to say that VS is real enough, and what is at question is the *contents* of it in relationship to the physical world. In general terms, realism is therefore defined by science as a relationship (or lack thereof) between what we perceive and what we know by other means (so-called scientific "instrumentalism"). As I commented earlier, this corresponds to what has been called "critical" realism.

So, then, once again, I pose the question: What do you mean, David, by the "living body" given this conceptual context?

"Perceptual body" then shares the same disadvantage as "perceptual world," which is now a standard term in research psychology. If we are to be consistent conceptually, we need to be consistent with our terms as much as possible, otherwise "body image" might be mistaken for being a kind of "visual image" (i.e. something imagined, rather than perceived, and a phantom limb is not imagined, it is perceived by the person experiencing it).

Schilder used the term Körperschema, after Henry Head's usage of Kant's term "schema." It is not clear to me whether by this Head meant the perceptual body or some sort of mental representation, because this is what he actually wrote (in 1920): "By means of perpetual alterations in position we are always building up unwittingly a model of ourselves, which is constantly changing. Every new posture or movement is registered on this plastic schema...." How this got translated as "body image" in the English-language version of Schilder's book, I do not know. His own German book, published in 1923, was indeed entitled just "Körperschema"

Just checking Schilder's book "Image and Appearance of the Human Body," I find that he writes: "[In his book] 'Körperschema' (schema of the body) . . . I tried there to study those mechanisms of the central nervous system which are of importance for the building up of the spatial image which everybody has about himself." This strikes me as a very strange way of describing how we perceive ourselves, but Schilder does link his notion with that of a Gestalt. He explicitly refers to the Berlin School, and also to Kant, William James, John Dewey and, last but not least, naive realism.

Yes, naive realism is clearly out of the question and off the table. What you called putative physical realism is even worse, as being a half baked mixture of naive realism and low level popular science. The kind of realism defined by what scientific instruments show is also more or less phony, for it takes instruments, laboratories, et cetera as just given, which makes it merely a slightly more sophisticated version of putative physical realism. No, but what is real has its own existence in some way as opposed to being only an object of awareness. (It "exists within itself" in this sense.) There is then the world of material objects that is real in this sense. Thus, Berkeley was wrong. Augustine and Aquinas would say God creates these objects, but that means He makes them to be actually real, and so there is not only the dreamscape that Berkeley claimed. The nature of this world as it exists within itself is then whatever it turns out to be.

Once again, I mean by "living body" in this context what Kohler meant by "organism." The living human animal is one material object among others within the real world of material objects. There is also self aware consciousness associated with such animals. (How this works is a further question down the line.) The body as experienced is then the animal organism as manifested within the consciousness of the given animal. So, when I say sensory impressions and their integration belong to the living body, I mean they belong to the vital functioning of the real material object that is the human animal. That is all.

I must be missing something, David, but as Watson says to Holmes, "I have no doubt that I am very stupid, but I must confess that I am unable to follow you." In Philosophy 101 the teacher asks, "What is real and how to we know that?" as a simple way of defining the study of ontology and epistemology, respectively. So, as a humble novice might ask, how do you know those things to 'exist in themselves'? By "those things," I am referring to "material objects." Already in comments I have made previously, "seeing is believing." Is reality something known or only believed?

The main point that I don't think is getting across from this desk to yours (or IPhones, as the case may be), is the "picture" of physical objects (and the physical world) painted by modern physics is not only paradoxical, but unrecognizable as anything corresponding to what we perceive. Is that clear enough?

As it happens, I myself have taught Introduction to Philosophy many times. Now, how do I know there is some real world of observable material objects that exist within themselves? The short answer is, by perceiving through the senses, and finding how this perception works, and learning how this sensory experience adds up, and knowing the implications of this structured experience. As I say, that is the short answer. The full answer runs to dozens or even scores of pages. (I know this the hard way, from writing my dissertation.) I would say reality is known in this way and on this basis.

But then, what about modern physics? Well, yes, the picture of the material world painted by modern physics is unrecognizable as anything corresponding to what people perceive. Of course, one can challenge modern physics, but presumably an ideally perfected physics would paint an at least equally unrecognizable picture. Where does it go from there? As a classical (but not naive) realsit, I would say what people perceive is (when all goes well) simply the manifestation within human awareness of the real material world. It is just that human sensory functioning turns out to be weak as regards reaching the underlying details that make the material world work.

Yes, I do, very much so. I am and remain a classical realist. The kicker comes with what is meant by the word "resembles" in this context. When all goes well (which is to say, when experience is veridical rather than deceptive), the features of experience map into the features of the material world in an appropriate way. (It would take a little too long to explain this mapping here.) I say there is the real material world that resembles the perceptual world in this limited way. But in fact, it would be better to say the perceptual resembles the material in this way, since the material world is the original, and the perceptual world is the reflection. All this is so even though, e. g., temperature as it exists among material things is very different from the simple quality of temperature that shows up in tactile experience.

On second thought, I believe I can illustrate what the mapping involves with a parallel case. A device that allows human subjects to detect infrared radiation shows the human subject what is there by translating the spread of facts regarding the infrared into a display of visible colors on a screen. Quite clearly, the display of visible colors is not there among the observed objects. Yet even so, the display of colors is an accurate image of the spread of facts about the infrared among the objects. For the display on the screen corresponds correctly to the spread of facts among the objects. As regards experience, the phenomenal display in consciousness is an accurate image of the relevant observable facts in the material world, at least when all goes well. For this display corresponds correctly to the structure of facts in the world.

A classical realist! With the befuddled popularity that relativism now enjoys in the humanities, classical realists are a vanishing breed.

Yes, "resembles" even as a word presents almost insuperable difficulties which, of course, are glossed over by the physical sciences. They just offer a "picture" like making infrared light "visible" to persuade one of the "reality" of such things, to cajole people (scientists included) into believing that there is indeed such a world "out there" (wherever that "there" is).

Since materialism was debunked already in the 19th century by Friedrich Albert Lange (d. 1875) in his "History of Materialism and Criticism of Its Importance," I am wondering how it has come to be resuscitated? As Lange said, "to think clearly about materialism is to refute it."

The notion of perception being "veridical" I suspect refers not to a relationship between perception and the physical world, but between different perceptions, as Mach argued (for one who, as Einstein acknowledged, was an influence on his own thinking about relativity).

Ordinarily when we assert the veridicality of something, it is established on the basis of evidence that is perceived, not from--somehow--comparing perceptions with the physical world itself, much as relativity depends upon relating observations and, Bernard Carr has agreed, physics has made no distinction between naive and any other kind of realism.

Both Pribram and Bohm have noted that much of our understanding of the universe has an optical character to it, that our ideas about objects are "lens-like" in their resolution (microscope, telescope), rather than showing the true state of affairs in which all life on earth is wrapped up in the radiation field of the sun, etc. So ideas about "resemblance," "reflection", "mappings," "screens," "displays," and analogies drawn from extending the *visible* spectrum to include the infrared, all come back to a sort of optically-oriented consciousness: vision which, as von Bekesy explained in his book "Sensory Inhibition" depend upon much lateral inhibition in the nervous system to appear (i.e., fussy signals being "neurally sharpened," etc). All of these things depend upon vision for their reality, if logical relations between visual or a potentially visualizable world that exists independently much as it *appears* to us.

Not only has Ray Tallis challenged this spurious view in his essay "The Disappearance of Appearance," it is what Bohm has challenged in his holonomic theory of the universe, which enjoys some support today in the world of cosmology.

With all the talk here of summarily rejected naive realism and representationalism, somehow reality itself has gotten lost along the way. What sort of realism are we permitted?

For anyone who may be interested, here are key passages from the posthumously published 1881 edition of Lange's "Materialism" explicitly dealing with its refutation:http://books.google.com/books?id=J089AAAAIAAJ&pg=PA112&dq=refute+inauthor:lange+inauthor:friedrich&hl=en&ei=uentTLKBCpLEsAOu-YHpCw&sa=X&oi=book_result&ct=result&resnum=3&ved=0CC0Q6AEwAg#v=onepage&q=refutation%20of%20materialism&f=false

Well, I gave the example of translating infrared into visible colors only as an example to illustrate in a "seat of the pants" way the idea of corresponding correctly. Of course, this idea must be developed much more carefully and abstractly in order to defend classical realism in any serious way. I sketched what is involved when I said "the features of experience map into the features of the material world in an appropriate way." The relevant concept of mapping into is taken over from set theory. On this basis, no, classical realism does not depend on picture thinking. The correspondence involved may be much less straightforward than the translation of infrared into visible colors, and what the material world is in itself may be truly exotic.

What about the concern that an experience is tested for being veridical or deceptive by being compared with other experiences and not by getting behind experience to apprehend directly the world as it is in itself? Well, yes, that too. But what is involved here can be understood in different ways. In Plato's Allegory of the Cave, Plato considered that the prisoners might try to find the correlations and patterns among the play of shadows on the wall. But even if they developed a very sophisticated understanding of these patterns and correlations, that kind of science would be not even preliminary to gaining any awareness of the heaven of Forms. Along this line, the objects that cast the shadows are the genuine reality of things on Earth, albeit a much lower level of genuine reality than the Forms. But their sophisticated knowledge regarding the shadows would not reach even the genuine reality of those objects! Instead, they must turn around and look, which corresponds to intellectual abstraction. So, yes, the question about being veridical or deceptive is based on comparing an experience with other experiences, but as Plato says elsewhere in the Republic, what is involved is intellectual criticsm. It is not about seeing whether the play of shadows goes smoothly as the prisoners might do.

Here is the difference this point makes. Physics had jolly well better allow for the difference between naive realism and other types of realism. For, if the material world should turn out to be unreal, what then? At worst, physics collapses as being mere fiction. (Given no material world, physics is about nothing real.) At best, physics is merely the phony science of the prisoners in Plato's Cave regarding the play of shadows on the wall.

Robert, I have been thinking, and I may have been too hasty. I continue to disbelieve that Descartes thought the soul to be located but not extended. However, I must admit I cannot altogether rule out the proposal, just because his theory was so spicy. But a question has arisen in my mind. Were you concerned only with the historical question about Descartes, or were you thinking that the proposal might be of some benefit if it could be made to work?

Are you saying then David that like the critical realist you believe reality can only be known abstractly through thought and reasoning (e.g., set theory)?

If we have a mathematical astrophysicist, viz. Bernard Carr, telling us that physics makes no distinction between "observation" in naive realism and in scientific realism, science has a big problem indeed.

Thinking of "mapping" in terms of pros hen equivocation we come back to the same defect that afflicts "brain mapping," i.e., mapping is only meaningful when one can (in principle) compare the map with that of which it is a map (this reasoning parallels points in Ray Tallis's Lexicon). But we can't do that with the physical world that is supposedly beyond our senses.

Further, it may be arguable that even the notion of mathematical "mapping into" (derived from geometrical projection prior to the notion being adopted in set theory) may depend upon that same sort of impossible relationship in this context, in which one is asserting being able to make relationships between perceptions and the physical (material) world.

Purely intellectual knowing, in contrast to perception, just seems to me to smuggle direct realism back into the familiar "picture" that entails being able to make a relationship between a perception and the physical world itself (yes, the old Ding an Sich).

As I have stated here previously my own contention is that "appearance" is, by nature, of low dimensionality, and that higher dimensional objects have no appearance for that reason (which also calls into question their very existence because of that). In the visual world, appearance requires a mapping down of dimensions--or so it seems, because we cannot really (again) make that comparison.

So I do think that the notion of observation in science and thus science itself is probably just wrong, even though it "works" like Crick's vacuum cleaner--that's the nature of its powerful appeal and also its deception: It is lawful but arbitrary.

To believe in science is just that--a belief, with articles of faith forming convictions just as strongly held as those in religion, and as we know from Cousin Richard, it has come into direct competition with religion for authority in arbitrating what is real.

But once one removes all the "hype" surrounding science, it really rests on some rather shaky a priori assumptions, not the least of which is that everything which is real is measurable. Why should that be the case? I maintain that qualia (groan) demonstrate that something can differ purely in quality, but not in quantity--except for one dimension: time. Two patches of color cannot both occupy the same spatial locus simultaneously. Fancy that!

What I have already said, too, is that the picture of the physical world painted by sub-atomic physics today is as ghostly as any spirit world which the skeptics categorically dismiss, seriously now proposing action-at-a-distance that 19th century materialism dismissed as being "magic." I believe this point has already been made many times before by other writers who did not fail to take notice.

William, you seem to be mixing different concerns together. As for what "Cousin Richard" means by science, that is his problem and his responsibility. But in fact, no, the affirmation of classical realism does not require that one be godless. Nor have you given any reason to think it does. You may be able to show that classical realism fails, but that is not the same as showing it leads to atheism. Again, classical realism does not require saying everything real is measurable. All it requires saying is that observed measurable things are real as far as they go. But these things could still be a very low level of reality, as was affirmed by Plato, Augustine, Thomas Aquinas, and to a lesser extent Aristotle. Along this line, for all classical realism has to say about it, there may very well be various things in higher dimensions that are beyond the reach of human subjects. All that is required is that, once again, the things and dimensions available to human observation are real as far as they go.

Now, I notice that you bring in sub-atomic physics with action-at-a-distance. At this point, then, I ask you to read my essay on quantum nonlocality at Robert's website (www.quantumrealism.net) and let me know what you think. When I have learned your reaction to this paper, I may know much better where we stand.

I did not suggest that adhering to classical realism (a philosophical doctrine) requires being godless. Scientific realism is not synonymous with classical realism, however. Dawkins and others argue that belief in God is inconsistent with science, because it is illogical and contradicted by the natural world (at least so scientific atheists try to argue).

The problem of perception is hampered, I believe, by the fetters of scientific mensuration, which *does* presuppose that its ontology be constructed solely on the basis of quantifiable phenomena, i.e., for science, more than repeatability, measurability is the sine qua non of being real.

Therefore from the standpoint of modern science, it is not clear what to make of Plato, Augustine, or Aquinas, because there is no indication in their writings that their ideas are based on anything empirical (let alone measurable) observation, but are derived instead chiefly from reasoning based on certain metaphysical presuppositions.

I should be interested, David, to read your paper on Bob's website, having known a number of physicists who have been involved with the problem of nonlocality, attending as I did Alain Aspect's first American lecture at Caltech on the topic back in the 1980s.

Well, but why should I give a rat's tail about the problems "from the standpoint of modern science" with traditional ideas? What you call scientific realism (which might better be called "scientism") is in fact also a philosophical doctrine, even though Dawkins and his crowd may think otherwise. It involves metaphysical presuppositions just as much as what Plato, Augustine, and Aquinas said. The difference is that the older people were rather more careful and critical in what they accepted and how they developed it, at least as regards specifically philosophical concerns. The truth is, scientism is at worst the half baked philosophical doctrine of amateur philosophers. At best, it is what results when those people take some provisional assumptions and defintions that are good for doing and interpreting work in the laboratory and then project all this uncritically far beyond its legitimate sphere.

No, affirming classical realism does not require accepting scientism, and neither does the pursuit of natural science, properly speaking. For one could hold and keep those provisional definitions and assumptions within their legitmate sphere, and avoid the wrongful projection. This would of course be the preferred way of doing things.

Good point about the "rat's tail," because one reader of our blog, who should have known better, less than a year ago questioned how there could still be philosophy above and beyond science. Perhaps he has since seen the light? Certainly scientists on the whole do not acknowledge that what they are doing is (natural) philosophy, and thus indeed grows out of philosophy. Dawkins, to my knowledge, has never explained his personal philosophy (if he even has one) except in terms of an anti-religion.

Alas, one must simply attribute that to sheer ignorance on their part, or, I could say more cynically, to a pernicious effort on the part of benighted reformers in education to blinker budding scientists into believing that theirs is the only true world view?

Given the remarks about the cruelty of Nature, the existence of pain, etc., whether made by Darwin or Attenborough, one gets the impression that it is Nature herself which has tended to shed doubt on God's existence, more than science--as if that doubt had been forced upon one by natural phenomena themselves. Of course, atheism itself is a very ancient position, not surprisingly associated closely with the philosophy of skepticism . . . .

So then, when I speak of classical realism, it is to be understood that no requirement of scientific mensuration is intended. If what is involved, or what there is, should turn out to be measurable, fine and dandy. But if not, that is all right too. With that as background, let me go back and see whether I can pick up some of the old threads.

To take the easiest point first, do I believe reality can only be known through thought and reasoning? Well, the word "known" is somewhat ambiguous here. Certainly, there is awreness of reality through sensory perception, even apart from or prior to rational thinking. But, in another way, the answer to the question is yes. Only through intellectual functioning can one entertain the questions of what is real or unreal, whether a given experience is veridical or deceptive, et cetera. Moreover, what gives this point serious punch is the very failure of naive realism. The line of least resistance is to take sensory experience at face value and beileve what shows up in experience is there in the observable world in just the way it shows up in experience. Of course, this turns out to be false, but how so? The attempt to follow this line through consistently leads into irresolvable paradoxes. Therefore, naive realism breaks down and fails. But to understand all this is the function of human adult critical intelligence, beyond what subrational animals and very young children have.

Moving on, does the physical world exist somehow beyond perception? Again, the word "beyond" is somewhat ambiguous. The physical world is prior to and independent of the perceptual world. On the other side, the physical world, so far from being divorced from the perceptual world, is exactly what is manifested in perception. The perceptual world is the reflection in consciousness of the physical world. The perceptual world is causally derived from the physical world and (when all goes well) corresponds to the physical world for this reason. This remains so even though naive realism is false, and so the correspondence involved is rather sophisticated and has to be understood at a fairly high level of abstraction. (Ordinary people may be said truly to know what it is for experience to be veridical or not, but that is so only because they see the truth through a glass darkly.) Along this line, the space that is manifested in my visual experience is public not private, not subjective, not part of my proprium or that of any other perceiving subject. On the other side, my visual space in the sense of the imagery in my consciousness of open expanses is of course part of my propium.

But last, and perhaps most serious, yes, there may be some puzzle about the idea of correspondence itself. I shall have to think about it and work through what I need to say about that.

It seems to me that maost of the assumptions David is expressing above are just what we are seeking to question.

For example, David writes, "On the other side, the physical world, so far from being divorced from the perceptual world, is exactly what is manifested in perception. The perceptual world is the reflection in consciousness of the physical world." That's news to me. Do you really think, David, that has been proven beyond a shadow of a doubt? I think not, but much hinges on what you mean by "manifested" and "reflection," having already commented, as I have, on reflection being a word derived from optics and seeing, even though here David may be using it in a figurative sense.

Yes, of course I am using the word "reflection" in a figurative sense here. I should have thought it was clear enough as a dead metaphor. The perceptual world is, so to speak, the image or copy in consciousness, and the physical world is the original. That is all. Nothing in particular is claimed or implied here about the processes inside the perceiving subject whereby this copy or image is established, starting from the impressions the subject receives from having the physical world affect him. All that is claimed, for now, is that the copy is correct, in more or less the (indirect) way the spread of colors on the infrared scope are a correct image of the relevant physical facts when all goes well.

Do I think all this is proved beyond a shadow of a doubt? No, of course not! I think this is the correct default position, the presumptive appearance of what is going on with perceiving through the senses. But there is no guarantee. Even the most sophisticated version of this kind of classical realism might end up leading into irresolvable paradoxes, perhaps in some subtle or hidden way. If this should turn out to be so, then sophisticated classical realism fails, just as much as naive realism. Again, even apart from such paradoxes, further empirical evidence could disprove classical realism. In one way, all that can be said is that classical realism seems to survive objections, and the opposition is up against an extremely stiff challenge. But hey, as the song says, who knows what tomorrow brings?

I rather assumed David was using reflection in a figurative sense, but it is one of those words that exemplifies pros hen equivocation (Aristotle): All senses of it tend to point to a single relatively constant central sense, in this case, *seeing one's own reflection,* first and foremost, with whatever may also be reflected around that being secondary. And as Burns wrote in his "To A Louse, On Seeing One On A Lady's Bonnet At Church," "O wad some Pow'r the giftie gie us, To see oursels as others see us!" Science would have us believe that the universe "sees us" as being an infinitesimal speck of no consequence--ergo, a completely depersonalized universe is what surrounds us, to which only science holds the key.

Personally, I, too, tend to favor some form of realism, but these days I am more inclined to believe that perceiving it (or knowing it) does not involve anything like a "reflection" but more like a process of "realization," that reality is resolved like an image is, rather perception of it being reflection. That implies reality is self-reflexive in some sense.

Reality and the real are again words that have different senses. If they also exhibit pros hen equivocation, though, there should be one primary sense from which the other senses of the word stem, and I doubt it is one dependent upon the intellect, as David suggests, but more akin to what I have been saying here: "Seeing is believing," and that reality is as much a kind of belief as a hypothesized condition of things. Remember, for a long time, Mach didn't believe in the reality of atoms, which he dismissed as being "things of thought."

To reply to David's question about Descartes, Descartes has not been called the "father of modern philosophy" for nothing, although scholastsic thought definitely creeps in, as with his claim that there is more reality in an infinite substance than a finite substance in his cosmological proof for the existence of God in the Third Meditation. In arguing for the pineal gland as the seat of the soul, I also read him as suggesting that that was the location for a causal interaction between the spatially unextended mind and the brain, and I think that he definitely held a representational theory of perception. Beyond this I would agree that there is room for different interpretations; but regardless I think that there is a possible theory holding that the mind is not spatial but has a spatial location, and perhaps this theory should be looked at more since it is one way to differentiate among different spatially unextended minds. It is not my theory though since my position is that conscious experience is spatial, and possesses a two-dimensional topology.With respect to issues being raised about resemblance between visual experience and the structure of physical objects being perceived, I think that you have to look at invariants under projection, such as the cross ratio, and even here the resemblance is only with macroscopic physical spatial properties. It is also possible to fool the system here with illusions. A further complication is that of size and shape constancy, as talked about by Robert Thouless when he discusses the "phenomenal regression to the real object." Incidentally, as far as I know this is the same Robert Thouless who investigated psychic phenomena and coined the term "psi."

Since our topic here mainly concerns spatial phenomena, I'm not sure how relevant Descartes' views really are, especially since there is no indication that he thought VS was unextended mind, though I must say I am intrigued by his idea that reality can be quantified in terms of spatial magnitude, i.e., that something infinite is "more" real than something finite. Some sort of "reality quotient" I take it?

In any case, I don't see how Descartes could have held a representational theory of perception, given that VS is manifestly extended, as John has been telling us now for over 50 years.

I don't see how it is possible for something to occupy a point in space and itself be unextended. That strikes me as being a logical contradiction. Perhaps I am wrong.

Again, Bob seems to presuppose macroscopic physical objects that are in some way similar to perceived counterparts, but then argues that the similarity can only be ascertained abstractly. This goes back to the point I made about direct realism being smuggled in through the back door by way of the mind, i.e., through reasoning, and it seems to me that it falls prey to the same pitfall that one can really make a comparison--if only a mental one, derived through abstraction--between the perceived world and the physical one.

Of course, science doesn't seem the least bit bothered by this problem, and just continues on its merry way oblivious to the conceptual defect.

For this reason, "illusions," I suggest, refer to relationships *between* perceptions, and the same for shape constancy, rather than relationships between perceptual objects and (putative) physical ones. I believe this is what we ordinarily mean by an illusion, assuming that one kind of perception is true, and another not.

As Kant says in his Logic, a concept becomes more abstract the more things are left out of it which, if applied to physical objects, includes their appearance (Ray Tallis). Mathematical formulations IMO are not exempt from that IMO.

Yes, right. As I said before, the soul must be spatially located in some way, given that this particular soul is associated with this particular body and no other. Once again, the question is, what way? The idea of the soul as located but not extended has the advantage of allowing for numerical differentiation, as Robert said, yet still keeping the soul as indivisible, so as not to violate the insight from Descartes about self aware consciousness. On the other side, if the soul is to be located in the same way as the body, Augustine and Thomas Aquinas would have two obvious objections, but these might not apply to Descartes. First, given that the soul is to be contained in space in the same way as the body, the soul is then subject to material restrictions in the same way as the body, which is contrary to the exalted character required for reasoning. But then, Descartes downgraded the traditional division between sense and intellect. Second, given that the soul is confined to just one point, it seems there will not be the function of developing and maintaining the body. But then, Descartes denied this function. So, perhaps the right interpretation of Descartes is what Robert said, after all.

I think it can be argued that, whether associated with the pineal because it is the only single organ that Descartes could find in the brain to associate with the soul, or not, there is a fundamental logical problem of how an unextended entity would be able to do anything whatever with an extended one such as VS.

Not quite by chance I found online a lecture given last year by Olivier Boulnois, a professor of medieval philosophy at the Sorbonne, concerning the *Imago Dei* (the image of God). As he speaks about much of what we have been deliberating over on this thread, you might find his paper both interesting and quite relevant, as it discusses the whole metaphysical background behind the idea of images in general:http://vimeo.com/8030578

What about the claim that the idea of illusion refers to relations among experiences, instead of to relations between experiences and some (alleged) external reality? This claim is almost correct, but not exactly so. Sensory perception turns out be such that, in order to describe rightly one's own experiences, one must refer (at least implicity) to real things in the real world that, so to speak, "stand behind" these experiences. This fact is the ultimate foundation of classical realism. To be sure, there is the basis to speak of experience in this way only because sensory experience is fairly richly structured instead of being chaotic. So, yes, in one way, the relations among experiences are where the action is. But still, the very nature of this concept of being real is to reach beyond experience.

Again, the whole basis for thinking a given experience to be an illusion is that it does not fit rightly into the structure of experience as a whole. But then again, this question of fitting experiences together arises only on the assumption that these experiences refer to real things in the real world. (Where it is given that experiences are a pure phenomenal display, with no claim to refer to anything beyond themselves, as with dreams, there is no problem about fitting these experiences together.) So, here too, the very nature of the concept of illusion is to reach beyond experience.

But even given all this, what does it really mean to say experience corresponds to objects?There is no direct access to the objects by which one can ascertain independently what the correlations with experience are and how they work. Therefore, the idea of correspondence at stake here may seem to be a wrongful projection onto reality of realtions found within experience. But this is not so, for one can think of correspondence very abstractly. This is the point of my earlier talk about set theory. In that case, however, the idea of correspondence might seem to be so highly abstract as to be kind of empty. But that too is not quite correct. How does it work in real life? A human subject starts with naive realism. As he matures and learns, he comes to know that this will not work. So, he figures that there is some much more sophisticated version of correspondence instead. As he acquires more and more of philosophy, natural science, and mathematics, the human subject comes to understand more and more of what should be discarded and what should be kept in his view of what it is for experience to manifest real things in the real world. So, no, the idea of correspondence is not empty. Its content is what inquiry shows to be appropriate.

One point to observe is that all this may even be compatible with what William proposed about the nature of reality. The claim that real objects stand behind experience could perhaps be reconciled with some version of the claim that the reality of these objects is somehow imperfect or unfulfilled unless and until these objects are manifested in conscious experience. Of course, this reconciliation would lead in fairly short order into at least theism, if not full blown idealism. But then perhaps that is what the truth turns out to be.

As we study visual illusions in the Center for Brain and Cognition at UCSD, what becomes apparent is that the typical visual illusion is interpreted by a percipient relative to another visual perception that is deemed correct by comparison/contrast, and is therefore real, because naive realism--our everyday mode of mentation--refers not to something beyond what we see, but indeed to just what we see, and trusting what we see, moreover--and in most cases that "reality" is just another "view" of something seen, until another illusion comes along.

Perceptual reality quite simply *is* reality for most people, and they don't think about reality being "behind" or "beyond" the things they see, except in that sense of the word that implies something unseen becoming seen (or known through language).

On this account I would deny that ordinary understanding of illusion entails reaching beyond experience, but merely to other experiences, which are collectively deemed to be "real."

We *assume* that all these things we see in "normal" perception exist when we are not looking at them--an assumption that may prove to be partly or even largely untenable. It is scientific realism as much as anything that wants to shift the locus of reality from perception to something beyond perception, e.g., something that can only be known mathematically.

"What does it really mean to say experience corresponds to objects"? David asks. If we think about talk of experience, I suspect that it will be the case that we do not ordinarily pose that question in the first instance. One does not say, for example, that they "experience" a table or tree. Talk of objects is therefore different from talk of experience, if not mutually exclusive or largely so. I very much doubt that the average person ever knows what is meant by "naive realism" in relation to some other form of realism; this is reserved for philosophers and other thinkers.

Perhaps it was James Hinton who first suggested that mankind was God becoming conscious of Self, but Jung certainly explored this theme in quite interesting ways in his famous essay, "The Answer to Job." This in turn is not too far from John Wheeler's "observer-participant" universe, at least in broad outline.

With respect to Bill's questioning whether Descartes held a representational theory of perception, I did want to cite some textual evidence. For one point, Descartes clearly holds a very broad sense of thought, definning it in the Second Meditation as doubting, understanding, affirming,, denying, willing, refusing, imagining and feeling.He goes on to say, regarding feeling that "Finally, I am the same who feels, that is to say, who perceives certain things, as by the organs of sense, since in truth I see light, I hear noise, I feel heat." Thus, in some sense, he clearly includes perception within the realm of thought. It is true though that Gassendi raises a point, which is analogous to what I think Bill has in mind, when in the Fifth Set of objections he asks "For, I ask you how do you think that you, an unextended subject, could receive into yourself the semblance or idea of a body which is extended? For, if such a semblance proceeds from the body, it is certainly corporeal and has parts outside of other parts, and consequently is corporeal. Or alternatively, whether or not its impression is due to some other source, since it necessarily is always an extended body it must still have parts, and consequently be extended. Obviously, if it has no parts how will it represent parts? If it has no extension how will it represent extension? If devoid of figure, how represent an object possessing figure? If it has no posiiton, how can it represent a thing which has upper and lower, right and left, and intermediate parts? If without variation how represent the various colors etc.? Therefore an idea appears not to lack extension utterly. But unless it is devoid of extension how can you, if unextended be its subject? How will you unite it to you? How lay hold of it? How will you be able to feel it gradually fade and finally vanish away?It is true that I don't find Descartes' reply all that satisfactory, when he talks about the mind applying itself to what is spatially extended without its being received into the mind, but I think he clearly is trying to defend some version of a representational theory here.

Thanks for these passages, Bob. But I don't see that in the one passage Descartes is necessarily connecting perceiving with thinking, only with the "I."

It has been awhile since I thought about efforts to make sense of Descartes' position (including Gassendi's), but I thought the consensus of opinion was that Descartes was not referring to perceptions as being unextended.

Something that strikes me as being relevant here is the idea that the truth is undivided which, in turn, may relate to the idea of Gestalt and Ganzheit: These are wholes, i.e., whole figures/configurations, or, in the case of Ganzheit *whole experiences* so that it may be possible to conceive of VS as being an *undivided whole.*

As probably most of you have gleaned, I am all for historical analysis in trying to resolve a problem that may have plagued thought on a topic, even for millennia. That said, are Descartes' views on an unextended mind interacting with the brain anything but a historical curiosity at this point in time? Certainly they do not figure in contemporary thought on the subject, and I doubt few today think of the mind as being unextended.

David has gone to some pains to elucidate the metaphysical background of Descartes' thought in this connection, but it occurs to me that nobody in philosophy and the sciences today are thinking about unextended entities when talking about manifestly extended ones. Perhaps what would be useful, then, is to know the source of the idea that something can indeed be unextended. David?

Well, yes, it is true that very few thinkers at the present day would affirm Cartesian dualism. The problem is, Cartesian dualism is often enough the framework that people are reacting against, even at the present day.

As near as I can figure, the idea that something real can be unextended goes back at least to Plato. He believed the heaven of Forms is not subject to material restrictions or limitations. Again, the Forms are not made of up of parts or pieces in any straightforward way. As you said, truth is undivided. Plato took this idea and ran with it.

Along this line, it is not quite true that no one in philosophy or science thinks about unextended entities when talking about extended things. In computer science, people talk about the algorithms that the machines implement. But of course, an algorithm is a mathematical structure, and Plato would be justified from his own standpoint in saying an algorithm exists first of all in the heaven of Forms. Can something concrete also be unextended? Well, Plato said the soul must be "like" the Forms in order to be aware of the Forms.

What I want to know is what happens when God is subtracted from Descartes' "equation." What remains? Surely vision scientists are not still wrestling with God (at least that they are aware or say).

Being subject to "material restrictions or limitations" may not be covalent with being unextended, so I think we must read Plato very carefully to avoid potential self contradictions.

The nature of mathematical reality (cf. Popper's World 2) may be similar to some of the abstractions that Ray Tallis discusses in his Lexion, so I would not necessarily draw the conclusion that an algorithm can exist without extension.

There are two old maxims: "Like cannot cognize like" and "like cognizes like" (both have been attributed to Aristotle, but they may be pre-Socratic formulas). So I'm not sure which applies here.

Yeah, right. Now, William, long ago in this string, you said substance is extended ex definitione, and I asked what defintion of substance you were using in saying this. This question went unanswered, and so I ask again. As I said back then, traditionally in Western philosophy, one could understand by the word "substance" (1) something that exists within itself (and thus can be more or less of a "standalone unit"), or (2) something that can persist through change, or (3) something that can have any of a range of mutually exclusive attributes. None of these definitions has any obvious implication of being extended. So, once more, what idea of substance do you have in mind? For I expect this has very much to do with your reluctance to acknowledge anything unextended.

Sorry for not answering this question earlier--just an oversight, not an intentional omission (or evasion). In this context I was probably thinking of the generic scientific sense of the word, which is not far from ordinary usage, as when someone asks, "What is that yellow substance on your hand? Perhaps it is pollen from brushing against the flowers over there?" In other words, I was not thinking of all the various philosophical and metaphysical and other special (and more abstract) senses of the word, but something that can be connected with perceptual experience.